Audible railroad crossing warning signal



April 8, 1952 s. w. MADDEN 2,592,163

AUDIBLE RAILROAD CROSSING WARNING SIGNAL Filed sept. 7, 1949 2 SHEETS-SMT 1 April 8, 1952 s. w. MADDEN AUDIBLE RAILROAD CROSSING WARNING SIGNAL Filed Sept. '7, 1949 2 SHEETS-SI-{EET 2 INVENTOR.

Sydney W. Madden Patented Apr. 8, i952 AUDELE RAELROAD CRGSSING WARNING 'SIGNAL Sydney W. Madden, Chicago, Ill.

Application September 7, 1949., Serial No.. 114,346

1 Claim. l

My invention relates to .audible railroad crossing signals. Most railroad crossing signals in present use are of the bell ringing type, which have such a common sound as often to be ignored by motorists and pedestrians at .railroad crossings, as well as citen beingconfused with bell signals for other pur-poses. Therefore, it is a prime object of my invention to provide an audible railroad crossing warning signal in which the sound of `the onrushing train is picked up, amplied and audibly transmitted by loud speakers placed at railroad crossings, bringing a loud and realistic sound of the speeding railroad train, which would attract the attention or motorists rand pedestrians at the said railroad crossings, causing there to stop and thereby avoiding many railroad crossing accidents.

A further important object of my invention is `to provide an audible railroad crossing warning signal wherein the sound ci the rushing train vibrated through the rails is picked up by microphones spaced at intervals vand clamped to the said rails, to be carried to loud speakers placed at the railroad crossings,

A still further object of my invention is to provide an audible railroad crossing warning signal, having signal pick-up microphones attached or clamped in series to one oi the rails of the railroad track on both sides of the crossing for a suliicient distance to give ample warning of the oncoming train at the railroad crossing.

A further object of my invention is to provide an audible railroad crossing warning signal that is of simple design and construction and may be economically produced in quantity and duickly and easily installed.

@ther objects and advantages embraced in my invention will be disclosed in the following description and the accompanying illustrations, wherein like parts are designated by like numerals and in which;

Fig. 1 is a plan View of two parallel railroad tracks with a road intersection or crossing and showing the spacing of the rail attached microphones and their connections to loud speakers located one facing each way at the railroad crossing; electrical wiring having been omitted for clarity.

Fig. 2 is an enlarged cross section of one of the rails or" the railroad, showing the clamping attachment thereto of one of the microphone assemblies and its electrical connections.

Fig. 3 is a side View of the clamp attached microphone and a portion of the rail taken looking in the direction of arrows 3--3 on Fig. 2.

l il

Fig. i is a View of the loud 'speaker assembly mounted on a loud speaker supporting pole.

Fig. 5 is a view, partly in cross section, -of the loud speaker assembly, taken substantially on line 5-5 on Fig. 4.

Fig. 6 is a schematic wiring diagram voi the electrical connections between the microphone pick-up units, the amplifier and the loud speaker.

Referring to the illustrations, my invention is generally designatedlT and consists of a microphone kassembly E, and a loud speaker assembly E, inter-connected by an insulated cable i8. The

microphone assembly B consists vof a microphone it, within a waterproof .microphone -casing il, having a rubber sealing washer 3l 'about its mouth which is maintained in contact with the web portion M of a rail I5 between two of the ties 35 and held securely in place by a clamp i2. The said clamp l2 has a microphone attaching portion 3:4 to Vhold microphone B against the web lil of rail I5, and a clamp tightening screw i3 .as illustrated in Figs. 2 and 3. A microphone rground wire .l B connects the microphone to clamp l2 and a cable connecting wire ll would preferably run through a pipe or lead casing underground to the nearest telephone or telegraph post 36, which it would connect to the insulated cable I8. The said cable I8 would preferably be suspended along the telegraph posts which ordinarily run parallel to the railroad right-of-way and would be connected to amplifier connecting wire i9.

The loud speaker assemblies 9 consists of ampliers 2l) and loud speakers 23, mounted upon loud speaker supporting poles 25. The said supporting poles 25 would preferably be located one on either side of the railroad track or tracks. facing the direction of oncoming trame at the railroad crossing. Amplifier ground wires 2| connect to rail l5 to complete the circuit between the yamplifier 2G and microphone l0. Loud speaker wires 22 connect amplifier y20 to loud speaker 23 and amplifier power wiresl 24 providing electrical power to the said amplifier 23, are connected to any convenient source of electrical power.

Since most railroad trains are at least a quarter of a mile in length, therefore, the microphone units 8 would preferably be attached to the railroad tracks at quarter-mile intervals for a distance of about one and one-half miles either side of the railroad crossing 29. This would enable the warning sound from a train going as fast as one hundred miles an hour to be picked up by loud speakers 23 in suflicient time to permit the vehicles designated 30 in Fig. 1, or pedestrians to stop even before the train is visible. Any number of railroad tracks on the railroad right-ofway could be connected to the same set of loud speakers 23 at the crossing 29, with the microphones connected in series as shown in Fig. 1.

In the said Fig. 1, two tracks designated 21 and 28 are illustrated and trains designated 3l and 32 are shown approaching the railroad crossing 29 from opposite directions. Both trains would be invisible, due to trees 33 and a curve in the railroad tracks, to the motorists on crossing 29. However, due to my warning signal device the motorist would be warned in ample time to stop. The loud speaker 23 and amplier 20 would be incased in weatherproof and insulated casings and the cables interconnecting amplifiers and microphones would be insulated and waterproof.

A most important advantage in4 connection with my audible railroad crossing warning signal, is the fact that the actual sound of an onrushing railroad train transmitted through its wheels 26 to rail l5 and picked up by microphones 8 and loudspeakers 23, greatly amplified, is made audible at the railroad crossing to warn approaching pedestrians and vehicles before the oncoming train is visible, giving ample time for stopping and thus avoiding accidents.

The fact that it is the actual sound of the moving trains transmitted through the rail attached microphones and the loud speakers that is heard at the railroad crossing, makes for a particularly effective warning. No person would ignore the sound of an approaching train greatly amplied, whereas many people will ignore bell warnings.

Although I have herein described rather succinctly the nature and use of my invention so that persons skilled in the art will have no diniculty apprising themselves of the teachings thereof and, inasmuch as the disclosure is susceptible of various alterations, modiiications, and improvements, I hereby reserve the right to all modifications, alterations, and improvements 4 falling within the scope and spirit of my invention, as well as any modifications that are embraced suggestively in the accompanying drawings, and any that may come within the purview of the foregoing description; my invention to be limited only by the appended claim.

Having thus disclosed and revealed my invention, what I claim as new and desire to secure by Letters Patent is:

An audible railroad warning signal comprising, in combination with railroad tracks and truck wheels riding thereupon; a multiple number of microphone assemblies secured to the web portion of the said railroad tracks in spaced relation to react directly to the vibrations thereof caused by the said truck wheels at a time when the said truck wheels are directly over any of the said microphone assemblies; a source of electrical energy; a phonetic amplifier connected electrically to the said source of electrical energy; a loud speaker electrically connected to the said phonetic amplier; and an electrical wiring circuit connecting in parallel the said microphone assemblies to the said phonetic ampliier and to the said loud speaker.

SYDNEY W. MADDEN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,059,263 Bennett Apr. 15, 1913 1,748,965 Watson Mar. 4, 1930 1,775,675 Gherassimoi Sept. 16, 1930 1,788,182 Zierdt Jan. 6, 1931 1,846,032 Hart Feb. 23, 1932 2,175,740 Charles Oct. 10, 1939 FOREIGN PATENTS Number Country Date 149 Great Britain Jan. 2, 1907 

